Some of the definitions used in 1960 differ from those used in 1950. These changes were made after consultation with users of census data in order to improve the statistics, even though it was recognized that comparability would be affected. The Definitions and Explanations should be interpreted in the context of the 1960 Censuses, in which data were collected by a combination of self-enumeration, direct interview, and observation by the enumerator.

The definitions below are consistent with the instructions given to the enumerator. As in all surveys, there were some failures to execute the instructions exactly. Through the forms distributed to households, the respondents were given explanations of some of the questions more uniformly than would have been given in direct interviews. Nevertheless, it was not feasible to give the full instructions to the respondents, and some erroneous replies have undoubtedly gone undetected.

More complete discussions of the definitions of population and housing items are given in I96Q Census of Population, Volume I, Characteristics of the Population, Part 1, United States Summary, and each of the State parts, and in 1960 Census of Housing, Volume I, States and Small Areas.

Socioeconomic Status

The Census Bureau's interest in the measurement of socioeconomic status is not of recent origin. As long ago as 1897, William C. Hunt, for many years Chief Statistician for Population in the Bureau of the Census, combined occupational returns into four broad social classes for the Censuses of 1870, 1880, and 1890 in order to determine whether the long-term shift in the occupational composition of the labor force away from agricultural pursuits had resulted in any improvement in the social and economic welfare of the working population. 1 Many other attempts were made at measuring socioeconomic status, though each had its particular weaknesses. 2 The General scheme which was- developed for use in the 1960 Census utilizes certain features of procedures found in the social science literature and, with some additions and modifications, fits them into the census framework.

Occupation, educational attainment, and income are all related, though no one of them by itself is always an adequate indicator of socioeconomic status. The socioeconomic score which is presented here represents a combination of the scores which a person was assigned by virtue of the occupation and educational attainment of the chief income recipient in his family and of the current family income. For persons not in families, socioeconomic status was based on the individual's own occupation, education, and income. The scores for the three items were developed on the basis of 1950 Census data and more recent sample survey data and were assigned to individuals in terms of reports on occupation, educational attainment, and income as given in the 1960 Census. These scores were coded in the 5-percent sample of the 1960 Census.

The following paragraphs include a description of the procedures used in deriving the new socioeconomic measures and a discussion of some of the considerations that went into the choice of procedures.

1. The two measures, the socioeconomic status score and the status consistency type, were obtained by combining data on: (a) Occupation, (b) educational attainment, and (c) family income (or income of persons not in families).

2. These measures were constructed for chief income recipients. Such a person was identified for each family. Each unrelated individual years old and over in households, and each person in group quarters (including inmates of institutions, members of the Armed Forces in military barracks, students in college dormitories, and residents in rooming houses) was treated as a chief income recipient. (See point 4 for treatment of unrelated individuals under in households.)

3. The chief income recipient in a family was defined as that member of a family who had the largest total Income In 1959 (at least $1 more than any other family member). If the family head and one or more other family members had identical incomes and they had the highest incomes in the family, or if no family member had reported income, the family head was considered the chief income recipient. If two or more family members other than the head had equal and highest incomes, the first one listed was regarded as the chief income recipient.

4. The socioeconomic measures for chief income recipients in families were assigned to other family members. Since a child under 14 cannot reasonably be regarded as having a socioeconomic status independent of that of the household in which he lives, unrelated individuals under in households (mostly foster children) were assigned the same measures as the head of the household, on the assumption that such children Generally share the living conditions of the household head. In order to complete the assignment of scores for all persons, persons under 14 years old in group quarters were arbitrarily assigned zero income and persons under 5 years old in group quarters were also assigned no school years completed. All other unrelated individuals were assigned component scores based on their own characteristics.

5. The reported occupation for a chief income recipient was used, provided he was currently in the civilian labor force or, if not, had worked since 1950. Since the rank and duties of members of the Armed Forces are not known from the census, chief income recipients currently in the Armed Forces were assigned a uniform occupation rating. For a chief income recipient who did not report his occupation or who had not worked since 1950, his score on education was assigned as his score on occupation also.

6. The socioeconomic status score was determined in the following way: (a) the occupation, education, and family income for the chief income recipient were identified. (b) The scores corresponding to the reported occupation, education, and family income of the chief income recipient were then determined by referring to a list of scores assigned to the various occupations and educational and income levels. (For list of scores, see appendixes I-IV.) (c) A simple average of the three component scores was computed; and the result was rounded to the nearest whole score.

The scores for each component item are distributed so that about 10 percent of the persons fall in each tenth of the distribution of scores for that item. If the component item scores were perfectly correlated, the distribution of the average (overall socioeconomic status score) would have 10 percent of the persons in each tenth of the distribution. The socioeconomic scores obtained by averaging the component scores are, as one would expect from the methods employed, distributed so that larger percentages of persons are in the central part of the distribution of scores and smaller percentages are at the extremes. (See section below on "Uses and Limitations of the Data" for a fuller explanation.)

7. The status consistency type was determined in the following way, using the three scores identified in 6(b) above:
a. If the range between the highest and lowest scores was 20 or less, recode 1 was assigned.
b. If the range between the highest and lowest scores exceeded 20, and the range between the medium and lowest scores was 20 or less and less than the range between the 'highest and medium scores:
(1) Recode 2 was assigned if the income score was highest
(2) Recode 4 was assigned if the education score was highest
(3) Recode 6 was assigned if the occupation score was highest.
c. If the range between the highest and lowest scores exceeded 20 and the range between the highest and medium scores was 20 or less and equal to or less than the range between the medium and lowest scores:
(1) Code 3 was assigned if the income score was lowest
(2) Code 5 was assigned if the education score was lowest
(3) Code 7 was assigned if the occupation score was lowest.
d. If the range between the highest and medium scores and the medium and lowest scores each exceeded 20:
(1) Code 8 was assigned if the occupation score was highest and income score lowest
(2) Code 9 was assigned if the occupation score was highest and education score lowest
(3) Code 10 was assigned if the education score was highest and occupation score lowest
(4) Code 11 was assigned if the education score was highest and income score lowest
(5) Code 12 was assigned if the income score was highest and occupation score lowest
(6) Code 13 was assigned if the income score was highest and education score lowest.

1. A basic assumption in the derivation of the socioeconomic measures is that the status level of a family is determined largely by the status attributes of the family breadwinner and that the socioeconomic measures for the chief income recipient of a family thus should be assigned to other family members.

2. The component items of the measures (occupation, education, and income) were selected because they represent somewhat different aspects of socioeconomic status and, in addition, because they are items which are periodically included in the Current Population Survey and in other population censuses and surveys conducted by the Bureau of the Census.

3. The choice of a particular index of each component item was based, in part, on the kinds of data available in census reports and, in part, on the expected uses to which the socioeconomic data would be put. Family income, rather than the income of the chief income recipient, was chosen because it was felt that the socioeconomic status of a family was related more closely to the family income than to the income of the chief earner.

4. The scores assigned to the categories of the component items were derived as follows: (a) The scores for education were obtained by computing a cumulative percentage distribution by education of chief income recipients in families as of 1959. (For example, persons who had completed five or more years of college were found to be distributed between the 96th and 100th percentiles.) The score assigned to each category of education was the midpoint of the cumulative percentage interval for the category. (For example, a score of 98 was assigned to persons who had completed five or more years of college), (b) the scores for family income were obtained in a similar manner. (c) The scores for detailed occupations were based on the most recently available data, those for males 14 years old and over in the experienced civilian labor force as of 1950- The detailed occupations were scored according to the combined average levels of education and income for the given occupation. Thus, the score obtained is an average score for the occupation and it contributes an independent effect to the total socioeconomic score, which includes also the individual's actual educational and income levels. Using the number of workers in each occupation, a cumulative percentage distribution was obtained. The score for a given occupation was then determined by taking the midpoint of the cumulative percentage interval for that occupation.

The occupational scores obtained by this procedure indicate the position of the average person in a given occupation, based on the education and income distributions for that occupation. This score may differ from that which would be assigned on the basis of judgments or other determinations about the prestige of the occupation. Although prestige ratings of detailed occupations may have been desired for use in this socioeconomic analysis, no adequate basis for deriving such prestige ratings was available and the procedure used here to score the occupations was deemed to be useful.
The standards (or basic information) on which the scores were based refer to a particular point in time. Present evidence indicates that the average of the component scores for a given type of population group would change very little over a period of time; however, for future historical analysis, the standards could be revised periodically to take into consideration changes in the distribution of the items over time.

Summary definitions of the basic items used in the derivation of the socioeconomic measures are shown below. More detailed Definitions and Explanations can be found in 1960 Census of Population, Volume I, Characteristics of the Population, Part 1, United States Summary.

The data on Years of School Completed were derived from combinations of the answers to the two questions: (a) "What is the highest grade (or year) of regular school he has ever attended?" and (b) "Did he finish this grade (or year)?" Enumerators were instructed to obtain the approximate equivalent grade in the American school system for persons whose highest grade of attendance was in a foreign school system, whose highest level of attendance was in an ungraded school, whose highest level of schooling was measured by "readers," or whose training by a tutor was regarded as qualifying under the "regular" school definition. Persons were to answer "No" to the second question if they were attending school, had completed only part of a grade before they dropped out, or failed to pass the last grade attended.

The occupational classification system developed for the 1960 Census consists of 494 items, 297 of which are specific occupation categories and the remainder of which are subgroups (mainly on the basis of industry) of 13 of the occupation categories. The composition of the 297 categories is shown in the publication, U.S. Bureau of the Census, 1960 Census of Population, Classified Index of Occupations and Industries, U.S. Government Printing Office, Washington, D.C., 1960.

Total family income, as used here, refers to the sum of amounts reported separately for wage or salary income, self-employment income, and other income for all family members. Wage or salary income is defined as the total money earnings received for work performed as an employee. It represents the amount received before deductions for personal income taxes, Social Security, bond purchases, union dues, etc. Self-employment income is defined as net money income (gross receipts minus operating expenses) from a business, farm, or professional enterprise in which the person was engaged on his own account. Other income includes money income received from such sources as net rents, interest, dividends, Social Security benefits, pensions, veterans' payments, unemployment insurance, and public assistance or other governmental payments, and periodic receipts from insurance policies or annuities. Not included as income are money received from the sale of property (unless the recipient was engaged in the business of selling such property), the value of income "in kind," withdrawals of bank deposits, money borrowed, tax refunds, and gifts and lump-sum inheritances or insurance payments. Although the time period covered by the income statistics is the calendar year 1959, the composition of families refers to the time of enumeration. For most of the families, however, the income reported was received by persons who were members of the family throughout 1959.

The socioeconomic scores and status consistency types were designed for comparative analysis and were not intended as a basis for establishing absolute levels of socioeconomic status or consistency. For instance, when the techniques for computing these socioeconomic scores are applied to farm occupations, the Component scores on occupation and family income, in many cases, are lower than they would be if an adjustment had been introduced to compensate for the fact that these farm workers receive part of their income in the form of housing and goods produced and consumed on the farm, rather than in money. The same applies to many religious and social welfare occupations, which often include housing and other nonmonetary forms of income. However, no adjustments were made in Bureau of the Census tabulations of socioeconomic scores for non-money income.

In addition to having limited absolute meaning, the measures used in this report represent only one approach to studying socioeconomic status in relation to other factors. They may be most useful where the analyst wants to compare different areas or population subgroups, or where socioeconomic status is needed as a control in studying other relationships. Other approaches may be more useful for other purposes; for example, in testing particular hypotheses involving socioeconomic components, a more appropriate procedure may be to use a multiple regression equation incorporating the variables whose effect is to be tested. Furthermore, the use of the present measures presupposes the availability of data on all of the component items. Where such information is lacking, as where only occupation data are available, other measures must be used. (When data on the component items are available but cannot be classified into the detailed categories used in deriving the census socioeconomic classifications, however, the present measures may still be used. Scores for major occupation groups are shown in appendix II. Scores for other component categories, such as other occupational groupings and broader intervals of education and family income, cart be obtained by writing to the Chief, Population Division, Bureau of the Census, Washington, D.C. 20233.)

The tables in this report present characteristics of the population by 12 classes of socioeconomic status scores, as illustrated by table A. All classes have a range of 10 except those between 20 and 29 and between 70 and 79, where the range is 5. These classes of range 5 were created so that the distribution of scores can also be divided into four parts: 0 to 24, 25 to 49, 50 to 74, and 75 to 99.

The methodology used in computing the socioeconomic status scores results in the assignment of larger numbers of persons to the central part of the distribution and smaller numbers to the extremes. For instance, 15.0 percent of the total population have scores in the 50 to 59 class, whereas only 5.4 percent have scores in the 90 to 99 class. This is the result of obtaining the socioeconomic status score as a mean of the three component items: education, income, and occupation. For instance, a chief income recipient with an education score of 49 (completed 3 years of high school), an income score of 69 (family income $6,500- $6,999), and an occupation score of 35 (a carpenter), is assigned a socioeconomic status score of (49 + 69 + 35) /3 or 51. The scores of each component item are distributed so that about 10 percent of the persons in the universe of all chief income recipients fall in each tenth of the range, 0-99; but the socioeconomic status score, because it is an average of the three component items, is an intermediate value. Therefore, relatively large numbers of persons in the total population fall in the intermediate classes and relatively small numbers in the extreme classes.

Table A. Socioeconomic Status of the Population, By Age and Sex, For the United States: 1960 (Numbers in thousands. Based on 5-percent sample)

The median is presented in connection with the socioeconomic score and with the data on value and gross rent of housing units. The median is the value which divides the distribution into two equal parts, one-half the cases falling "below this value and one- half the cases exceeding this value.

In General, the urban population comprises all persons living in Urbanized Areas and in places of 2,500 inhabitants or more outside Urbanized Areas. More specifically, according to the definition adopted for use in the 1960 Census, the urban population comprises all persons living in (a) places of 2,500 inhabitants or more incorporated as cities, boroughs, villages, and towns (except towns in New England, New York, and Wisconsin); (b) the densely settled urban fringe, whether incorporated or unincorporated, of Urbanized Areas; (c) towns, in New England and townships in New Jersey and Pennsylvania which contain no incorporated municipalities as subdivisions and have either 25,000 inhabitants or more or a population of 2,500 to 25,000 and a density of 1,500 persons or more per square mile; (d) counties in States other than the Hew England States, New Jersey, and Pennsylvania that have no incorporated municipalities within their boundaries and have a density of 1,500 persons or more per square mile; and (e) unincorporated places of 2,500 inhabitants or more. The population not classified as urban constitutes the rural population.

The rural population is subdivided into the rural-farm population, which comprises all rural residents living on farms, and the rural-nonfarm population, which comprises the remaining rural population. In the 1960 Census, the farm population consists of persons living in rural territory on places of 10 or more acres from which sales of farm products amounted to $50 or more in 1959 or on places of less than 10 acres from which sales of farm products amounted to $250 or more in 1959. All persons living in group quarters are classified as nonfarm except the relatively few living in workers' quarters (including quarters for migratory agricultural workers) that are located on a farm or ranch.

The population residing in standard metropolitan statistical areas (SMSA's) constitutes the metropolitan population. Except in New England, an SMSA is a county or group of contiguous counties which contains at least one city of 50,000 inhabitants or more, or "twin cities" with a combined population of at least 50,000. In addition to the county, or counties, containing such a city or cities, contiguous counties are included in an SMSA if, according to certain criteria, they are essentially metropolitan in character and are socially and economically integrated with the central city. In New England, SMSA's consist of towns and cities, rather than counties.
With a few exceptions, central cities are determined according to the following criteria:

1. The largest city in an SMSA is always a central city.

One or two additional cities may be secondary central cities on the basis and in the order of the following criteria:

a. The additional city or cities have at least 250,000 inhabitants.
b. The additional city or cities have a population of one-third or more of that of the largest city and a minimum population of 25,000.

The nonmetropolitan population includes all persons residing outside SMSA's.

The term "color" refers to the division of population into two groups, white and nonwhite. The color group designated as "nonwhite" consists of such races as the Negro, American Indian, Japanese, Chinese, Filipino, Korean, Hawaiian, Asian Indian, Eskimo, Aleut, and Malayan races. Persons of Mexican birth or ancestry who are not definitely of Indian or other nonwhite race are classified as white.

In addition to persons of Negro and of mixed Negro and white descent this classification includes persons of mixed Indian and Negro descent, unless the Indian ancestry predominates or unless the individual is regarded as an Indian in the community.

Persons of mixed racial parentage are classified according to the race of the nonwhite parent, and mixtures of nonwhite races are classified according to the race of the father, with the special exceptions noted above.

In order to obtain data on Spanish- and Mexican- Americans for areas of the United States where most of them live, white persons of Spanish surname were distinguished separately in five Southwestern States (Arizona, California, Colorado, New Mexico, and Texas) during the processing operations. Puerto Ricans comprise persons born in Puerto Rico and persons born in the United States or its possessions with one or both parents born in Puerto Rico.

This category comprises persons born in the United States, the Commonwealth of Puerto Rico, or a possession of the United States; persons born in a foreign country or at sea who have at least one native American parent; and persons whose place of birth was not reported and whose census report contained no contradictory information, such as an entry of a language spoken prior to coming to the United States.

Persons of foreign stock are classified in this report according to their "ethnic origin," on the basis of country of birth for the foreign born and parents' country of birth for the native of foreign or mixed parentage. Natives of foreign parentage whose parents were born in different countries are classified according to the country of birth of the father. Natives of mixed parentage are classified according to the country of birth of the foreign-born parent. The classification by country of origin is based on international boundaries as recognized by the United States Government on April 1, 1960, although there may have been some deviation from the rules where respondents were unaware of changes in boundaries or jurisdiction.

In tables 5 and 6, information on ethnic origin is shown for white persons only and is in terms of broad regions rather than individual countries. A list of the countries included in these groupings is shown in the PC(2)-5B report, Educational Attainment.

Residence on April 1, 1955, is the usual place of residence five years prior to enumeration. The category "same house" includes all persons 5 years old and over who were reported as living in the same house on the date of enumeration ' in 1960 and five years prior to enumeration. Included in the group are persons who had never moved during the five years as well as those who had moved but by 1960 had _returned to their 1955 residence. The category "different house in the U.S." includes persons who, on April 1, 1955, lived in the United States in a different house from the one they occupied on April 1, 1960. This category was subdivided into three groups according to their 1955 residence, viz., "different house, same county," "different county, same State," and "different State." The category "abroad" includes those with residence in a foreign country or an outlying area of the United States in 1955- (In the coding of this item, persons who lived in Alaska or Hawaii in 1955 but in other States in 1960 were classified as living in. a noncontiguous State in 19550 Persons 5 years old and over who had indicated they had moved into their present residence after April 1, 1955, but for whom sufficiently complete and consistent information regarding residence on April 1, 1955, was not collected are counted as "not reported."

This classification refers to the Marital Status of the person at the time of enumeration. Persons classified as "married" comprise, therefore, both those who have been married only once and those who remarried after having been widowed or divorced. Persons reported as separated (either legally separated or otherwise absent from the spouse because of marital discord) are classified as a subcategory of married persons. The enumerators were instructed to report persons in common-law marriages as married and persons whose only marriage had been annulled as single.

In the 1960 Census, persons in the 25-percent sample who had ever been married were asked the date of their first marriage; this information was tabulated in terms of year or calendar quarter and year. Age at First Marriage was derived from date (calendar quarter and year) of birth and date of first marriage and represents age in completed years at first marriage.

A household consists of all the persons who occupy a housing unit. A house, an apartment or other group of rooms, or a single room is regarded as a housing unit when it is occupied or intended for occupancy as separate living quarters, that is, when the occupants do not live and eat with any other persons in the structure and there is either (1) direct access from the outside or through a common hall or (2) a kitchen or cooking equipment for the exclusive use of the occupants of the unit.

All persons who are not members of the household are classified as living in group quarters. Most of the persons in group quarters live in rooming houses, college dormitories, military barracks, or institutions. Inmates of institutions are persons for whom care or custody is provided in such places as homes for delinquent or dependent children; homes and schools for the mentally or physically handicapped; places providing specialized medical care for persons with mental disorders, tuberculosis, or other chronic disease; nursing and domiciliary homes for the aged and dependent; prisons; and jails.

A family consists of two or more persons in the same household who are related to each other by blood, marriage, or adoption; all persons living in one household who are related to each other are regarded as one family. An unrelated individual Is a member of a household who is not related to anyone else in the household, or is a person living in group quarters who is not an inmate of an institution.

The head of the household or family is the member reported as the head by the household respondent. However, if a married woman living with her husband is reported as the head, her husband is classified as the head for the purpose of census tabulations.

"Stage of the Family Life Cycle" in table 15 refers to a division of all husband-wife families by age of head, presence of children, and the ages of the children. The various stages describe the passing of a family through the cycle of a husband and wife before they have children (no Own Children), while they have preschool-age children (under 6), while they have school-age children (6 to 17), and after their children have all grown and left home.

The number of children ever born includes children born to the woman before her present marriage, children no longer living, and children away from home, as well as those of her children who were still living in the home. Although the question on children ever born was asked only of women reported as having been married, the data are not limited to legitimate births.

A housing unit is "occupied" if it is the usual place of residence of the person or group of persons living in it at the time of enumeration. Included are units occupied by persons who are only temporarily absent, such as persons on vacation. Units occupied by persons with no usual place of residence are also considered occupied.

A housing unit is "owner occupied" If the owner or co-owner lives in the unit, even if It is mortgaged or not fully paid for. The head himself need not be the owner. All other occupied units are classified as "renter occupied," whether or not cash rent is paid. Examples of units for which no cash rent is paid include units occupied in exchange for services rendered, units owned by relatives and occupied without payment of rent, and units occupied by sharecroppers.

Value is the respondent's estimate of how much the property would sell for on the current market (April 1960). Value data are restricted to owner- occupied units having only one housing unit in the property and no business. Units in multiunit structures and trailers were excluded from the tabulations, and in rural territory, units on farms and all units on places of 10 acres or more (whether farm or non- farm) also were excluded.

Gross rent is based on the information reported for contract rent and the cost of utilities and fuel. Contract rent is the monthly rent agreed upon regardless of any furnishings, utilities, or services that may he included. The computed rent termed "gross rent" is the contract rent plus the average monthly cost of utilities (water, electricity, gas) and fuels such as wood, coal, and oil if these items are paid for by the renter. Thus, gross rent eliminates differentials which result from varying practices with respect to the inclusion of utilities and fuel as part of the rental payment. Rent data exclude rents for units in rural-farm territory.

The enumerator determined the condition of the housing unit by observation, on the basis of specified criteria. Nevertheless, the application of these criteria involved some judgment on the part of the individual enumerator. The training program for enumerators was designed to minimize differences in judgment.
Sound housing is defined as that which has no defects, or only slight defects which are normally corrected during the course of regular maintenance.
Deteriorating housing needs more repair than would be provided in the course of regular maintenance. Such housing has one or more defects of an intermediate nature that must be corrected if the unit is to continue to provide safe and adequate shelter.

Dilapidated housing does not provide safe and adequate shelter and in its present condition endangers the health, safety, or well-being of the occupants. Such housing has one or more critical defects, or has a combination of intermediate defects in sufficient number or extent to require considerable repair or rebuilding, or is of inadequate original construction. Critical defects result from continued neglect or lack of repair, or indicate serious damage to the structure.

"Availability of housing facilities" in table 20 refers to the classification of household heads by the number of seven listed facilities that they have available for their use. The seven facilities include clothes washing machine, clothes dryer, home food freezer, telephone, air conditioning, television set, and radio sets (2 or more). The availability of each facility is defined as follows:

A clothes washing machine or dryer owned by a member of the household was to be reported, whether it was located in the housing unit or elsewhere on the property. Machines used but not owned by members of the household, such as those provided by the management of an apartment building, were not to be reported. A washer-dryer combination was counted as two facilities.

A home food freezer is defined as an appliance, separate from the refrigerator, which freezes food and keeps food frozen. The freezer must be located in the housing unit or elsewhere on the property. Excluded is a freezer combined in the same cabinet with a refrigerator, even if it has a separate door.

A unit is classified as having a telephone if there is a telephone available to the occupants of the unit for receiving calls. The telephone may be located inside or outside the housing unit, and one telephone may serve the occupants of several units.

Air conditioning is defined as the cooling of air by refrigerating apparatus. Excluded are evaporative coolers and fans or blowers which are not connected to a refrigerating apparatus. Separate statistics are shown in table 32 for primary families having air conditioners designed to cool one room and for those designed to cool more than one room (including central systems). A central system is an installation which air-conditions a number of rooms. In an apartment building, a central system usually provides air conditioning for all the apartments.

Radio and television sets of all kinds located in the unit were to be included in the count-floor, table, built-in, portable, and combination with radio or phonograph. Sets in working order and sets being repaired were to be counted. A combination radio-television set was to be reported both as a television and as a radio set. In computing scores for availability of facilities, radio sets were counted only if there were two or more available. Automobile radios, sending-receiving sets, and crystal sets were not included.